mtx_trylock

 

C

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Program utilities

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Error handling

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Strings library

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Input/output support

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Concurrency support (C11)

Technical Specifications

Symbol index

 

Concurrency support library

Threads thrd_create thrd_equal thrd_current    thrd_sleep thrd_yield thrd_exit thrd_detach thrd_join thrd_successthrd_timedoutthrd_busythrd_nomemthrd_error    Atomic operations atomic_init ATOMIC_VAR_INIT (until C23) ATOMIC_***_LOCK_FREE atomic_is_lock_free atomic_store atomic_load atomic_exchange atomic_compare_exchange atomic_fetch_add atomic_fetch_sub atomic_fetch_or atomic_fetch_xor atomic_fetch_and

Atomic flags atomic_flag ATOMIC_FLAG_INIT atomic_flag_test_and_set atomic_flag_clear Memory ordering memory_order kill_dependency atomic_thread_fence atomic_signal_fence Mutual exclusion mtx_init mtx_lock mtx_timedlock mtx_trylock call_once mtx_unlock mtx_destroy mtx_plainmtx_recursivemtx_timed Condition variables cnd_init cnd_signal cnd_broadcast cnd_wait cnd_timedwait cnd_destroy Thread-local storage thread_local TSS_DTOR_ITERATIONS    tss_create tss_get tss_set tss_delete

 

Defined in header <threads.h>
int mtx_trylock( mtx_t *mutex );		(since C11)

Tries to lock the mutex pointed to by mutex without blocking. Returns immediately if the mutex is already locked.

Prior calls to mtx_unlock on the same mutex synchronize-with this operation (if this operation succeeds), and all lock/unlock operations on any given mutex form a single total order (similar to the modification order of an atomic)

Parameters

mutex

-

pointer to the mutex to lock

Return value

thrd_success if successful, thrd_busy if the mutex has already been locked or due to a spurious failure to acquire an available mutex, thrd_error if an error occurs.

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C standards.

DR	Applied to	Behavior as published	Correct behavior
DR 470	C11	mtx_trylock was not allowed to fail spuriously	allowed

References

• C17 standard (ISO/IEC 9899:2018):

• 7.26.4.5 The mtx_trylock function (p: 278-279)

• C11 standard (ISO/IEC 9899:2011):

• 7.26.4.5 The mtx_trylock function (p: 382)

See also

mtx_lock (C11)	blocks until locks a mutex (function)
mtx_timedlock (C11)	blocks until locks a mutex or times out (function)
mtx_unlock (C11)	unlocks a mutex (function)